YC-1的神經保護作用機轉之探討

Abstract

巴金森氏症是現今最常見的神經退化性疾病之一，在目前的醫療只能治標不能治本，並且對於其致病機轉仍然不清楚的情況下，研發新的治療藥物並研究致病原因是非常必要的。 我們發現YC-1可以減少SH-SY5Y受到MPP+和6-OHDA的損害，SH-SY5Y是神經母細胞瘤的細胞株，具有多巴胺神經的特徵，對MPP+和6-OHDA具有敏感性，而YC-1可以增加sGC對NO的感受性，是一個sGC 活化劑，早先被發現具有抗血小板凝集和使血管平滑肌放鬆的功能，之後又陸續有報告指出它在其他疾病模式下也有不同的效果。 YC-1可以抑制MPP+或6-OHDA造成SH-SY5Y細胞凋亡達50%以上，並且可以抑制MPP+或6-OHDA造成的Bcl-2 減少, PARP 斷裂, 以及procaspase-3 活化；我們認為YC-1並非藉由NO/cGMP/PKG訊息路徑達到神經保護的作用，因為給予NOS抑制劑(L-NAME, 7-NI)，sGC抑制劑(ODQ)，PKG抑制劑(KT 5823, RP-8-Br-PET-cGMPS)都不能有效抑制YC-1的作用；而且直接給予cGMP類似物(8-Br-cGMP)並無法減少MPP+和6-OHDA造成的細胞毒性，所以YC-1在這樣的實驗模式裡應該是透過其他路徑達到其神經保護的作用；此外，我們發現PKG抑制劑(KT 5823)可以保護SH-SY5Y細胞，降低MPP+或6-OHDA造成的細胞毒性，因此，我們認為PKG也許參與在MPP+或6-OHDA的毒性機轉當中，或者KT 5823有其他的作用標的。 綜合以上實驗結果，我們認為YC-1可以減少神經細胞受到MPP+或6-OHDA的傷害，有潛力發展成治療巴金森氏症的藥物，而它在細胞及動物模式的保護機轉則仍需再進一步探討。

Parkinson’s disease(PD) is one of the most common neurodegeneration diseases in the world and yet lacks a thorough cure. The studies on its pathogenesis as well as the development of new therapies are indispensable. A compound, YC-1, which was first reported to have an anti-platelet function, is found here to be neuroprotective in SH-SY5Y human neuroblastoma cell line. It can protect SH-SY5Y cells from the damage caused by MPP+ or 6-OHDA. YC-1 inhibited MPP+ or 6-OHDA-induced cell death, which is evaluated by MTT reaction, PI flow cytometry, and DAPI staining. YC-1 also inhibited Bcl-2 degradation, PARP cleavage, and procaspase-3 activation caused by MPP+ or 6-OHDA. As a sGC activator, we then examined whether YC-1 protects SH-SY5Y through NO-cGMP-PKG pathway. However, all inhibitors acting in NO-cGMP-PKG pathway failed to suppress the effect of YC-1. The neuroprotective mechanism of YC-1 needs further investigation. On the contrary, the cell death induced by MPP+ or 6-OHDA was partially reversed by KT 5823, a PKG inhibitor, suggesting that PKG inhibition may be protective in dopaminergic neuronal cell line exposed to MPP+ or 6-OHDA. On the other hand, KT 5823 may also act on other targets except PKG. In conclusion, here we demonstrate that YC-1 possesses neuroprotective quality. Although the mechanisms of action of YC-1 in cell line and in animal model are still required to be investigated, YC-1 is likely to be a potential compound to treat PD patients.